Sanitary articles such as sanitary napkins, baby diapers, absorbent inserts, tampons, and absorbent adult incontinence articles are well-known in the art. Typically all these articles comprise a wearer facing surface and a garment facing surface. The wearer facing surface receives from the wearer of such articles bodily discharges such as urine, vaginal discharges or menses, to be absorbed. In order for the article to store the liquid, the wearer facing surface has to be liquid permeable while maintaining the integrity of the outer wearer facing surface of the absorbent article and preventing liquid absorbed by the article from flowing back out onto a wearer. This wearer facing surface is provided by a topsheet.
Well-known topsheets in the art of absorbent articles are non-woven fabrics and films. Non-woven fabrics are made of fibers which by their nature provide non-linear apertures for liquid transport, although such fabrics may further be modified with an arrangement of apertures. Films have to be rendered permeable by aperturing.
Films suitable for use as topsheets are generally made of polymeric material and typically comprise apertures or orifices which have been engineered to provide certain characteristics. These apertures are defined by sidewalls, which extend from the surface of the film. The apertures may vary in shape and size but have commonly been provided in a single preferred size and shape. An example of such a known topsheet is described in U.S. Pat. No. 3,929,135 to Thompson, incorporated herein by reference. The sidewalls of the apertures define the amount of extension, if any, beyond the plane of the film thickness and the direction of such extensions. The sidewalls of the apertures also can be provided in the shape of a funnel.
Film topsheets are preferred over fabric topsheets by some users since they can provide a relatively cleaner-looking surface even after liquid has passed through since they do not generally retain liquids on their surfaces. However, some users may find film topsheets to be irritating or chafing, especially along the edges of the product, since the pattern (i.e., the size, shape, and spacing) of apertures provided by the topsheet extends across the entire topsheet, and the aperture pattern that is preferred for passing fluid quickly may not be preferred for facing against the user's inner thighs along the side edges of the product.
A method that has been used to overcome the disadvantages of side edge discomfort while retaining the benefits of quick fluid passage is that of using an apertured film topsheet over the entire surface of the absorbent product, and then covering the apertured film along the side edges of the product with a layer of nonwoven fabric. The apertured film provides good fluid handling properties in the center of the product where the fluid enters, and the nonwoven imparts greater comfort to the user by providing soft fabric along the product's edges. However, this adds material cost to the product and an extra step in the manufacturing process.
An additional disadvantage of known apertured films is that, because of their uniform aperture patterns, their fluid transport properties are generally uniform as well. Attempts have been made to improve the fluid transport characteristics of certain apertured films by the inclusion of larger apertures in and amongst the apertures of the uniform aperture pattern. However, this method still produces an apertured film with a uniform aperture arrangement, albeit an arrangement consisting of large holes and small holes. Furthermore, although the larger apertures may allow for the passage of fluid into an underlying absorbent layer, these same larger apertures may be more likely to allow the absorbed fluid to pass back out of the apertures when the wetted absorbent layer is subjected to pressure. In other words, absorbed fluid may be squeezed out of the absorbent layer, through the large holes, and onto the skin of a wearer of the absorbent article.
It is therefore an object of this invention to provide an apertured web suitable for use as an absorbent article topsheet with two or more different and discrete, that is, noncontinuous and individually distinct, zones within a single topsheet.